Navigation system with electroacoustic leader cables



7, 1963 1... BATCHELDER 3,089,117

NAVIGATION SYSTEM WITH ELECTROACOUSTIC LEADER CABLES Filed Feb. 10, 1960INVENTOR. Jaw! ame fia/e/ar A/fforne/ United States Patent 3,089,117NAVIGATION SYSTEM WITH ELECTROACOUSTIC LEADER CABLES LaurenceBatchelder, Cambridge, Mass., assiguor, by

mesne assignments, to the United States of America as represented by theSecretary of the Navy Filed Feb. 10, 1960, Ser. No. 7,954 8 Claims. (Cl.340-4) The present invention relates to a novel and improved shipnavigation system and more particularly to novel and improved apparatusfor facilitating navigation of a ship through a predetermined navigablearea during a mine sweeping operation and for fixing the position ofmine devices detected therewithin.

In a mine sweeping operation, it is ordinarily necessary to tow a sweepover a series of parallel courses. Each course must be accuratelylocated and followed so that the swept paths overlap sufliciently toavoid the possibility of a hiatus therebetween. Adjacent swept paths,however, should not overlap so much as to destroy efliciency unduly.When a mine is detected, its exact position must oftentimes be recordedso that disposal can subsequently be effected.

Although various types of navigational aides for ship guidance during amine sweeping operation or for guidance through a narrow channelhavebeen devised heretofore, considerable ditficulty has beenexperienced in the past in providing a system which is relatively simplein construction and yet provides a high degree of navigational precisionand accuracy.

Accordingly, it is a principal object of the present invention toprovide a novel and improved guidance system for a ship whereby adefined course or channel may be accurately and precisely navigated.

It is a further object of the present invention to provide a novel andimproved ship guidance system which is characterized by a pair ofcontinuous conductors disposed along opposite sides of a predeterminedchannel whereby the position of the ship within the channel may becontinuously and precisely defined.

A still further object of the present invention is to provide a noveland improved ship navigational system for use during a mine sweepingoperation.

Still another object of the present invention is to provide novel andimproved apparatus for detecting and recording the exact position of themines in a predetermined area during a mine sweeping operation.

Another object of the present invention is to provide novel and improvedchannel guidance and/or mine sweeper navigational and detectionequipment which is suitable for rapid installation aboard any vessel,which may be easily removed therefrom, and which continuously providesthe navigator or pilot with the exact position of the vessel and/ ormines disposed within the channel.

Other objects and many of the attendant advantages of this inventionwill be readily appreciated as the same becomes better understood byreference to the following detailed description when considered inconnection with the accompanying drawing wherein:

FIG. 1 is a perspective view showing the manner in which the channeldefining cables of the present invention are positioned along the bed ofthe channel annd energized by suitable sonic or ultrasonic energysources.v

FIG. 2 is a geometric diagram which illustrates the manner in which theposition of the ship within the channel may be computed. I

Referring first to FIG. 1 of the drawing, the width of the channel orgeneral area 3 which is to be navigated or swept of mine devices or thelike 4 is delineated by the continuous coaxial cables 5 and 6 which areanchored at the bottom of the channel in any suitable manner alongopposite sides thereof. The length of the channel is preferablysubdivided into a plurality of subsections. One such channel subsectionis shown in the drawing at 7. Each subsection of the channel isdefinedby the cross channel coaxial cables 8 and 9.

The central conductor of cable 5 iselectrically connected by means ofconductor 10 in series With the secondary winding of transformer 11, thebattery or other suitable source of direct current potential 12, and theexternal conductor of cable 6. The primary winding of transformer 11 isenergized in any suitable manner such as by means of the conventionalsonic or ultrasonic frequency generator source or the like 13. Thecentral conductor of cable 6 is electrically connected by means ofconductor 14 in series with the secondary winding of transformer 15, thebattery or other suitable source of direct current potential 16, and theexternal conductor of cable 5. The primary winding of transformer 15 isenergized in any suitable manner such as by means of the conventionalsonic or ultrasonic frequency generator source or the like 17. Theoperating frequencies of the generator sources 13 and 17 areindividually selected such that the signals generated thereby can easilybe isolated in the ship carried hydrophone equipment 18 which detectsthe electrostrictively produced sound waves, and in the receiver or thelike 18a which detects the electromagnetic waves and provides the zerotime reference signals for the system.

The cables 8 and 9 which define the channel subsection 7 are similarlyenergized respectively by the sonic or ultrasonic frequency generatorsources or the like 20 and 21. Thus, the central conductor of cable 8 iselectrically connected by means of conductor 22 in series with thesecondary winding of transformer 23, the DC. source 24, and the externalconductor of cable 9. The primary winding of transformer 23 is energizedby generator 20. The central conductor of cable 9 is electricallyconnected by means of conductor 25 in series with the secondary windingof transformer 26, the DC. source 27, and the external conductor ofcable 8. The primary winding of transformer 26 is energized by means ofgenerator 21. The operating frequencies of generators 20 and 21 areselected so that they can easily be isolated in the hydrophone equipment18 and in the receiver 18a on the ship 19 one from another and also fromthe signals of generators 13 and 17.

In operation the manner in which the ship can be con tinuously locatedwithin the channel between cables 5 and 6 is geometrically illustratedin FIG. 2. As shown therein, the bed of the channel or other body ofwater to be navigated and/or demined is represented by the X-axis of thecoordinate system. The cables on either side of the channel are locatedat f; and f the foci of the ellipse E. The position of the shipwithinthe channel is shown at S. Using the Pythagorean theorem Inasmuch as c,the distance of one of the cables from the center of the channel, is aconstant, x the position of the ship with respect to the center of thechannel can easily be computed by developing D.C. voltages proportionalto dB and d and applying these voltages difierentially to a suitableindicating or recording device.

Voltages proportional to d and d for the computation of d and d aredeveloped from the time intervals required for the waves produced by thephenomenon of electrostriction in the cables to reach the ship-carriedhydrophone.

Inasmuch as the details of the circuitry on the ship used to detect,square, and combine the signals from the cables differentially form nopart of the present invention, and since many suitable conventionalcircuits are well known and available, the same are not provided hereinfor the sake of simplicity.

The apparatus herein described provides not only a convenient andreliable means for navigating the ship through the prearranged channel,but also provides a unique navigational aid for the accurate guidance ofthe ship in a mine sweeping operation when it is necessary to tow asweep over a series of parallelcourses. Each course must be located suchthat the swept paths overlap sufiiciently to avoid the possibility of ahiatus therebetween, and at the same time not overlap so much as to beunduly inefficient. With the navigational aid of the present invention,the exact position of the ship can be continuously plotted so that thesweeping operation can be performed with accuracy and dispatch.

Where suitable mine disposal means are not carried on the ship 19, theexact position of the ship and the mine detecting equipment thereon mustbe recorded during the sweeping operation. and their associatedcircuits, which function in the same manner as the above describedcircuits of cables 5 and 6 provide the desired accurate record of thelongitudinal position of the ship when a mine is detected. By thusplotting the exact position of each mine detected within the channel,the disposal operation can be carried out at any suitable later time.

Although the principle of electrostriction is employed to energizecables 5, 6, 8, and 9 and to transmit signals theerfrom, it is to beunderstood that similar circuitry employing the principle ofmagnetstriction or utilizing the similar piezoelectric effect could beused without departing from the spirit or scope of the presentinvention.

Obviously many modifications and variations of the present invention arepossible in the light of the above teachings. It is therefore to beunderstood that within the scope of the appended claims the inventionmay be practiced otherwise than as specifically described.

What is claimed is:

The cross channel cables 8 and 9.

1. Apparatus for continuously indicating the position of a ship within achannel said apparatus comprising a pair of coaxial cables positioned onthe bed of the channel, said cables being disposed along oppositelongitudinal sides of the channel; a high frequency energy source foreach cable; a first circuit which includes in series the centralconductor of one cable, one high frequency source, and the peripheralconductor of the other cable; and a second circuit which includes inseries the central conductor of the other cable, the other highfrequency source, and the peripheral conductor of the one cable.

2. The apparatus of claim 1 wherein the material from which the coaxialcables are constructed exhibits electrostrictive properties.

3, The apparatus of claim 2 wherein means are provided for individuallypolarizing the said first and said second circuits.

4. The apparatus of claim 3 wherein the polarizing means include sourcesof direct current potential.

5. The apparatus of claim 1 further including a third and a fourthcoaxial cable, said third and fourth coaxial cables being spaced onefrom the other and disposed across the width of the channel; third andfourth high frequency sources; a third circuit which includes in seriesthe central conductor of the third cable, the third high frequencysource and the peripheral conductor of the fourth cable; and a fourthcircuit which includes in series the central conductor of the fourthcable, the fourth high frequency source, and the peripheral conductor ofthe third cable.

6. The apparatus of claim 5 wherein the material from which all thecables are constructed exhibits electrostrictive properties.

7. The apparatus of claim 6 wherein means are provided for individuallypolarizing the said circuits.

8. The apparatus of claim 7 wherein the polarizing means include sourcesof direct current potential.

References Cited in the file of this patent UNITED STATES PATENTS1,388,949 Hanson Aug. 30, 1921 2,391,079 Van Dyck Dec. 18, 19452,956,278 Branchu Oct. 11, 1960

1. APPARATUS FOR CONTINUOUSLY INDCATING THE POSITION OF A SHIP WITHIN ACHANNEL SAID APPARATUS COMPRISING A PAIR OF COAXIAL CABLES POSITIONED ONTHE BED OF THE CHANNEL, SAID CABLES BEING DISPOSED ALONG OPPOSITELONGITUDINAL SIDES OF THE CHANNEL; A HIGH FREQUENCY ENERGY SOURCE FOREACH CABLE; A FIRST CIRCUIT WHICH INCLUDES IN SERIES THE CENTRALCONDUCTOR OF ONE CABLE, ONE HIGH FREQUENCY SOURCE, AND THE PERIPHERALCONDUCTOR OF THE OTHER CABLE; AND A SECOND CIRCUIT WHICH INCLUDES INSERIES THE CENTRAL CON-